I dont need to materialize it more than once. But the concern is understood.
On Tuesday, October 27, 2015 at 3:03:42 PM UTC-4, √ wrote:
>
> This is not going to answer your question but:
>
> def toFlow(handler: Handler) = {
> var ctxt: Option[Context] = None <--- *DO NOT DO THIS*
>
> Flow[(Context, State)].map {
> (in: (Context, State)) => {
> ctxt match {
> case Some(last) => if (!last.equals(in._1)) {
> last.concludeContext()
> ctxt = Some(in._1)
> }
> case None => ctxt = Some(in._1)
> }
>
> handler.handleState(in._2)
> handler.concludeState(in._2)
> in
> }
> }
> }
>
> The problem is that now your Flow cannot be materialized more than once
> (until the previous has run to completion) simply because it is using
> global mutable state.
>
> On Tue, Oct 27, 2015 at 7:49 PM, Rich Henry <[email protected]
> <javascript:>> wrote:
>
>> *TL;DR -- Is there any way to provide an individual Flow component with
>> logic to execute on Graph completion?*
>>
>> I'm trying to wrap an existing API that is used like this:
>>
>> obj.handleContext(c1)
>> obj.handleState(s1)
>> obj.handleState(s2)
>> obj.handleState(sN)
>> obj.concludeContext(c1)
>>
>> .. in a flow, very much like this:
>>
>> def toFlow(handler: Handler) = {
>> var ctxt: Option[Context] = None
>>
>> Flow[(Context, State)].map {
>> (in: (Context, State)) => {
>> ctxt match {
>> case Some(last) => if (!last.equals(in._1)) {
>> last.concludeContext()
>> ctxt = Some(in._1)
>> }
>> case None => ctxt = Some(in._1)
>> }
>>
>> handler.handleState(in._2)
>> handler.concludeState(in._2)
>> in
>> }
>> }
>> }
>>
>>
>> I then combine the various handlers created using this method together
>> using ~> and use .grouped() and Sink.head to collect the resulting values.
>>
>>
>> *I need to call handler.concludeContext() on the last context passed in
>> to the flow on completion for each sub-flow.*
>>
>>
>> My backup plan it to wrap the flow components in another class that holds
>> the context and manually calling the conclude method on them en masse once
>> the flow completes, but would much prefer to use some built in mechanism
>> instead if there were one.
>>
>>
>> I'm also open to other strategies that may help me avoid being stateful,
>> but to date haven't thought of any.
>>
>> (I'm using akka-actor 2.4.0 and akka-streams-experiental 1.0)
>>
>> Thanks,
>> Rich
>>
>> --
>> >>>>>>>>>> Read the docs: http://akka.io/docs/
>> >>>>>>>>>> Check the FAQ:
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>
>
>
> --
> Cheers,
> √
>
--
>>>>>>>>>> Read the docs: http://akka.io/docs/
>>>>>>>>>> Check the FAQ:
>>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html
>>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user
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